In my opinion, the best chance for the Cataclysm community to get back on it's feet would be a complete realm reset and core overhaul to rerelease it as a hardcore pre-nerf(the state of early cata 4.0 infamous for it's hard and rewarding dungeons and its challenging and rich end-game) but on the 4.3.4 patch and release new raid tiers once every 1-1.5 years while also doing a bit of good advertisement like you did for Lordareon, and yes early cata is actually famous for its difficulty across the WoW community and is bound to bring people in, don't forget that atlantiss has been on Firelands content for way too long and noone is looking forward to Dragon Soul there, since alot of people are just Neltharion's pve migrants that play there for the past year or so. At least from the PVE scene which i'm most familiar with everyone seems to unanimously agree that the best period during cata was early 4.0 progression and while i'm not extremely knowledgable with the thoughts of pvpers on the matter i believe that a good chunk of them would be interested in the changes the different tiers bring like for example the lack of the pve weapons and trinkets that seem to dominate right now which would be replaced by select few decent pve trinkets that saw play in 4.0.6 but that didn't make such colossal impact to the scene. Also the resetting of the realm would bring back alot of people that dropped cataclysm during the late 2015-mid 2016 era where for people that just started out in the pvp scene they would be faced with endless stream of premades a generally not fun experience for people lacking the gear to even stand a chance and a time where to get in 2s full ruthless would be mandatory unless you had a friend to carry you and still you would more often than not que versus people in bis pvp/pve combos or carry teams.
Also to alot of people that have very negative emotions towards the idea of losing all the time they've sank into the realm, i understand you. I have reached a point where i own a total of 20 accounts(40% from friends that quit cata) and around 50 400+ ilvl toons while also having alot of now unobtainable things on my mains, but what all these years of continuous decline in population and interest has taught me is that, just like with the message of the ancient book Odyssey, it's not about the destination, it is all about the journey. In all the years i've spent in this community in this expansion the good and the bad i've made many priceless memories that are of much greater worth than any piece of virtual goodies i've ever got my hands on(rogue with norm and hc blf woo hoo) and at the end of the day those are the ones that will stay with me. While it is nice logging in on my bis toons on their extremely rare t11hc transmogs and always have people checking them out whispering me nice things etc, or just taking a walk to the usual spots me and my older guilds used to hang out, or even having the luck to run into anyone from back in the day and instantly recognize each other, all of that will soon amount to nothing if we aren't willing to sacrifice them now that they still hold some value so we create hope once more for the server we all love so much.
Also on the note of toxicity for anyone not playing currently on Neltharion, it's not like that in-game, at least here in the alliance side i feel like we are in the least toxic period neltharion has ever been into. Of course there will always be bad apples, and due to how humans work we tend to give alot more attention to them, but when it comes to groups and not just individuals in the larger community, groups as in guilds for example, things are very different from any other warmane realm i've played in. The top heroic raiding guilds accept anyone, and give new people chances, there are quite few people that actually make normal mode dragon souls with no achievement requirements or bull**** ilvl requirements, even tho i am in the high ranks of a top raiding guild and i can always just raid in guild and clear raids in an hour and be done with it, i rather prefer to actually get a bunch of new and old people on global and tryhard the content even if it means raiding for 5 hours straight because i know that out of these we'll get a couple of new raiders every week, and this attitude of the pve community in general has payed off and recently we've started having succesful dragon soul 25man heroics again during weekends.
There are alot of nice and passionate people on Neltharion, people that you generally won't find on forums, if you like Cataclysm as an expansion come pay us a visit, i'm always open to helping new people out as long as it goes along the lines of the old saying "Give a man a fish and you feed him for a day; teach a man to fish and you feed him for a lifetime." and if you're interested in pve feel free to pm me in-game @Chaosocial or /who Chaos to find me on my alts. And if you're more of a pvp guy it looks like this guy Horribul is doing what i'm doing in the pvp scene so hit him up.
For those of you that are part of the Neltharion community and feel ill of it keep in mind that we're the most engaged of all communities on Warmane and that's a fact, i was able to put together a dragon soul raid at 05:00am st which is when the population is at its lowest literally /who shown 35 people online on alliance and yet the engagement with the content is just so high that 1 in 3 randoms would be willing to actually go and raid on the spot. We might be the underdog realm but that's what makes us stronger, and at times like these instead of being toxic and fighting against each other with constant drama and guild breaks we seem (at least from my experience in-game) to have come together united and many of those infamous "toxic" people have left(Speaking for myself however i have personally contributed to the toxicity 2 years ago by making one of the most toxic raiding guilds <Abortion> which made alot of good people quit and for that i sincerely apologize).
Finally, it would be nice if an application form was created for volunteer community manager or game master work for neltharion specificly, it would make it easier to compile high priority issues that require immidiate attention by developers, it would help reinforce guidelines effectively in-game if game masters on neltharion are also people who actively play there and can get attention of issues on the spot, and it would also create a viewpoint from the in-game community's perspective of warmane actually starting taking care of it's cataclysm realm. Also many of us have good ideas to increase content engagement like lowering elite weapon's arena rating requirements to actually achievable numbers and including 2s rating to make ladders a bit more active again for the pvp side and in the pve side making heroic valor point items available outside of marketplace-only items by adding very low drop-rate tokens in Dragon Soul Heroic loot tables and adding a vendor to upgrade normal version valor point items with a token to heroic versions of the same items(like blizzard originally intended to do but scraped the idea) which would give incentive to people that are fully bis to raid on these toons again. Also another good idea on the cosmetic side is introducing the transmog scroll system to Cataclysm in the form of weapon transmog scrolls with less restrictions than the in-game transmog system that would allow for one-hand axe to one-hand sword transmogs and also legendary transmog scrolls with low drop-chance from the most challenging content to give a bit more engagement from the kinds of people that have gotten pretty much everything else when it comes to gear and only care about their looks at this point.
So that's all i had to say, if you've read this throu, i love you. I would love to hear some thoughts from both the community but also from the staff itself, there are still options left for Neltharion and we'd be fools to not take advantage of them.